1. Experimental and numerical studies of 3-D transitions & 2. Characteristics of some highly curvilinear flows

1. 3-D 转变的实验和数值研究

• 批准号: 7608-2013
• 负责人: Ramamurthy, Amruthur
• 金额: $ 2.04万
• 依托单位: Concordia University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=568521
• 关键词: 1.; Experimental; numerical; studies; transitions

Research proposal: 1. Channel transition flows 2. Highly curvilinear flows 1. The network of open channels supplying water to various end users from a reservoir can have a closed conduit or a rectangular concrete open channel attached to the reservoir to feed a larger trapezoidal earth channel. For efficient operation, the flow passes through a short transition. Reducing energy loss and secondary flow intensity are the main goals. Channel transitions should be shaped to limit energy losses by careful design that prevents flow separation. For instance, a warped transition linking a rectangular channel with a trapezoidal channel is a case in point. Reduced energy losses attain larger irrigation command areas. Reduced secondary flow intensity in downstream channels reduces channel erosion. The study investigates the characteristics of different transitions including the warped, wedged and cylindrical transitions. Transitions will be studied, after installing auxiliary devices (vanes & humps) to augment energy conservation and reduce secondary flow intensity. LDV (Laser Doppler velocimetry) and PIV (Particle Image Velocimetry) data will yield the mean and fluctuating velocity components to assess the energy conservation efficiency in transitions and reduction of secondary flow intensity in the downstream channels. Reynolds stress transport (RST) based CFD models will be developed to get the turbulent stresses. 2. In highly curvilinear flows, boundary layer approximations that permit one to assume that the stream wise velocity is dominant and that the transverse pressure gradient is negligible are not valid. Such flows occur in hydrocyclones, siphons and counter wall jets. To get a description of these flows, one seeks solutions that yield the details of turbulence behavior in terms of various scales, stresses and eddy characteristics. Both experimental studies and numerical modeling methods will be used. Siphons permit efficient ways of conserving stored water for end users. Improved hydrocyclones can segregate ingredients better. Efficient counter jets promote enhanced dilution of pollutants.

研究建议：1.航道过渡流2.高曲线水流 1.从水库向不同终端用户供水的明渠网络可以有封闭的管道或连接到水库的矩形混凝土明渠，为更大的梯形土槽供水。为了有效地运行，流程要经过一个短暂的过渡。降低能量损失和二次流强度是主要目标。通道转换的形状应通过防止流动分离的精心设计来限制能量损失。例如，连接矩形通道和梯形通道的扭曲过渡就是一个很好的例子。减少的能量损失可以扩大灌溉指挥区。下游河道二次流强度降低，减少了河道冲刷。研究了不同相变的特征，包括翘曲相变、楔形相变和柱形相变。在安装辅助装置(叶片和驼峰)后，将研究过渡，以加强节能和降低二次流强度。激光多普勒测速(LDV)和粒子图像测速(PIV)数据将产生平均速度分量和脉动速度分量，以评估下游航道在过渡和降低二次流强度时的节能效率。基于雷诺应力输运(RST)的CFD模型将被用来获得湍流应力。 2.在高度弯曲的流动中，边界层近似是无效的，这种近似允许人们假设流向速度占主导地位，而横向压力梯度可以忽略。这种流动发生在水力旋风分离器、虹吸管和壁面喷流中。为了得到对这些流动的描述，人们寻找解决方案，根据不同的尺度、应力和涡流特征来产生湍流行为的细节。实验研究和数值模拟方法都将被使用。 虹吸式供水系统为终端用户节约蓄水提供了有效的途径。改进后的水力旋流器能更好地分离原料。高效的反喷流促进了污染物的强化稀释。